diff options
Diffstat (limited to 'fs/overlayfs/dir.c')
| -rw-r--r-- | fs/overlayfs/dir.c | 152 |
1 files changed, 130 insertions, 22 deletions
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 0f8b4a719237..116f542442dd 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -14,6 +14,7 @@ #include <linux/posix_acl_xattr.h> #include <linux/atomic.h> #include <linux/ratelimit.h> +#include <linux/backing-file.h> #include "overlayfs.h" static unsigned short ovl_redirect_max = 256; @@ -260,14 +261,13 @@ static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry) * may not use to instantiate the new dentry. */ static int ovl_instantiate(struct dentry *dentry, struct inode *inode, - struct dentry *newdentry, bool hardlink) + struct dentry *newdentry, bool hardlink, struct file *tmpfile) { struct ovl_inode_params oip = { .upperdentry = newdentry, .newinode = inode, }; - ovl_dir_modified(dentry->d_parent, false); ovl_dentry_set_upper_alias(dentry); ovl_dentry_init_reval(dentry, newdentry, NULL); @@ -295,6 +295,9 @@ static int ovl_instantiate(struct dentry *dentry, struct inode *inode, inc_nlink(inode); } + if (tmpfile) + d_mark_tmpfile(tmpfile, inode); + d_instantiate(dentry, inode); if (inode != oip.newinode) { pr_warn_ratelimited("newly created inode found in cache (%pd2)\n", @@ -327,9 +330,6 @@ static int ovl_create_upper(struct dentry *dentry, struct inode *inode, struct dentry *newdentry; int err; - if (!attr->hardlink && !IS_POSIXACL(udir)) - attr->mode &= ~current_umask(); - inode_lock_nested(udir, I_MUTEX_PARENT); newdentry = ovl_create_real(ofs, udir, ovl_lookup_upper(ofs, dentry->d_name.name, @@ -345,7 +345,8 @@ static int ovl_create_upper(struct dentry *dentry, struct inode *inode, ovl_set_opaque(dentry, newdentry); } - err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink); + ovl_dir_modified(dentry->d_parent, false); + err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink, NULL); if (err) goto out_cleanup; out_unlock: @@ -529,7 +530,8 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode, if (err) goto out_cleanup; } - err = ovl_instantiate(dentry, inode, newdentry, hardlink); + ovl_dir_modified(dentry->d_parent, false); + err = ovl_instantiate(dentry, inode, newdentry, hardlink, NULL); if (err) { ovl_cleanup(ofs, udir, newdentry); dput(newdentry); @@ -551,12 +553,35 @@ out_cleanup: goto out_dput; } +static int ovl_setup_cred_for_create(struct dentry *dentry, struct inode *inode, + umode_t mode, const struct cred *old_cred) +{ + int err; + struct cred *override_cred; + + override_cred = prepare_creds(); + if (!override_cred) + return -ENOMEM; + + override_cred->fsuid = inode->i_uid; + override_cred->fsgid = inode->i_gid; + err = security_dentry_create_files_as(dentry, mode, &dentry->d_name, + old_cred, override_cred); + if (err) { + put_cred(override_cred); + return err; + } + put_cred(override_creds(override_cred)); + put_cred(override_cred); + + return 0; +} + static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, struct ovl_cattr *attr, bool origin) { int err; const struct cred *old_cred; - struct cred *override_cred; struct dentry *parent = dentry->d_parent; old_cred = ovl_override_creds(dentry->d_sb); @@ -572,10 +597,6 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, } if (!attr->hardlink) { - err = -ENOMEM; - override_cred = prepare_creds(); - if (!override_cred) - goto out_revert_creds; /* * In the creation cases(create, mkdir, mknod, symlink), * ovl should transfer current's fs{u,g}id to underlying @@ -589,17 +610,9 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, * create a new inode, so just use the ovl mounter's * fs{u,g}id. */ - override_cred->fsuid = inode->i_uid; - override_cred->fsgid = inode->i_gid; - err = security_dentry_create_files_as(dentry, - attr->mode, &dentry->d_name, old_cred, - override_cred); - if (err) { - put_cred(override_cred); + err = ovl_setup_cred_for_create(dentry, inode, attr->mode, old_cred); + if (err) goto out_revert_creds; - } - put_cred(override_creds(override_cred)); - put_cred(override_cred); } if (!ovl_dentry_is_whiteout(dentry)) @@ -1290,6 +1303,100 @@ out: return err; } +static int ovl_create_tmpfile(struct file *file, struct dentry *dentry, + struct inode *inode, umode_t mode) +{ + const struct cred *old_cred; + struct path realparentpath; + struct file *realfile; + struct dentry *newdentry; + /* It's okay to set O_NOATIME, since the owner will be current fsuid */ + int flags = file->f_flags | OVL_OPEN_FLAGS; + int err; + + err = ovl_copy_up(dentry->d_parent); + if (err) + return err; + + old_cred = ovl_override_creds(dentry->d_sb); + err = ovl_setup_cred_for_create(dentry, inode, mode, old_cred); + if (err) + goto out_revert_creds; + + ovl_path_upper(dentry->d_parent, &realparentpath); + realfile = backing_tmpfile_open(&file->f_path, flags, &realparentpath, + mode, current_cred()); + err = PTR_ERR_OR_ZERO(realfile); + pr_debug("tmpfile/open(%pd2, 0%o) = %i\n", realparentpath.dentry, mode, err); + if (err) + goto out_revert_creds; + + /* ovl_instantiate() consumes the newdentry reference on success */ + newdentry = dget(realfile->f_path.dentry); + err = ovl_instantiate(dentry, inode, newdentry, false, file); + if (!err) { + file->private_data = realfile; + } else { + dput(newdentry); + fput(realfile); + } +out_revert_creds: + revert_creds(old_cred); + return err; +} + +static int ovl_dummy_open(struct inode *inode, struct file *file) +{ + return 0; +} + +static int ovl_tmpfile(struct mnt_idmap *idmap, struct inode *dir, + struct file *file, umode_t mode) +{ + int err; + struct dentry *dentry = file->f_path.dentry; + struct inode *inode; + + if (!OVL_FS(dentry->d_sb)->tmpfile) + return -EOPNOTSUPP; + + err = ovl_want_write(dentry); + if (err) + return err; + + err = -ENOMEM; + inode = ovl_new_inode(dentry->d_sb, mode, 0); + if (!inode) + goto drop_write; + + inode_init_owner(&nop_mnt_idmap, inode, dir, mode); + err = ovl_create_tmpfile(file, dentry, inode, inode->i_mode); + if (err) + goto put_inode; + + /* + * Check if the preallocated inode was actually used. Having something + * else assigned to the dentry shouldn't happen as that would indicate + * that the backing tmpfile "leaked" out of overlayfs. + */ + err = -EIO; + if (WARN_ON(inode != d_inode(dentry))) + goto put_realfile; + + /* inode reference was transferred to dentry */ + inode = NULL; + err = finish_open(file, dentry, ovl_dummy_open); +put_realfile: + /* Without FMODE_OPENED ->release() won't be called on @file */ + if (!(file->f_mode & FMODE_OPENED)) + fput(file->private_data); +put_inode: + iput(inode); +drop_write: + ovl_drop_write(dentry); + return err; +} + const struct inode_operations ovl_dir_inode_operations = { .lookup = ovl_lookup, .mkdir = ovl_mkdir, @@ -1310,4 +1417,5 @@ const struct inode_operations ovl_dir_inode_operations = { .update_time = ovl_update_time, .fileattr_get = ovl_fileattr_get, .fileattr_set = ovl_fileattr_set, + .tmpfile = ovl_tmpfile, }; |